Left atrial volume index in highly trained athletes

Background: Increase of left atrial (LA) diameter in trained athletes has been regarded as another component of the "athlete's heart".

Aims: To evaluate the possible impact of competitive training on LA volume and to define reference values of LA volume index in athletes.

Methods and results: Six hundred fifteen consecutive elite athletes (370 endurance- [ATE] vs 245 strength-trained athletes [ATS]; 385 men; 28.4 +/- 10.2 years, range 18-40 years) underwent a comprehensive transthoracic echocardiography exam. LA maximal volume was measured at the point of mitral valve opening using the biplane area-length method, and corrected for body surface area. LA mild dilatation was defined as a LA volume index between 29 and 33 mL/m(2), while a moderate dilatation was identified by a LA volume index > or =34 mL/m(2). Left ventricular (LV) mass index and ejection fraction did not significantly differ between the 2 groups. Conversely, ATS showed increased body surface area, sum of wall thickness (septum + LV posterior wall), LV circumferential end-systolic stress (ESSc) and relative wall thickness, whereas LA volume index, LV stroke volume and LV end-diastolic volume were greater in ATE. The range of LA volume index was 26 to 36 mL/m(2) (mean 28.2 +/- 9.2) in men and 22 to 33 mL/m(2) (mean 26.5 +/- 7.2) in women (P < .01). LA volume index was mildly enlarged in 150 athletes (24.3%) and moderately enlarged only in 20, all males (3.2%). Mild mitral regurgitation was observed in 64 athletes (10.3%). LA volume index was significantly greater in ATE (P < .01). By multivariate analysis, the overall population type (P < .01) and duration (P < .01) of training and LV end-diastolic volume (P < .001) were the only independent predictors of LA volume index.

Conclusions: In a large population of highly trained athletes, a mild enlargement of LA volume index was relatively common and may be regarded as a physiologic adaptation to exercise conditioning.